Benjamin



B. S. ELROD BAH CASTING DIE AND METHOD FOR SEASONING THE SAME Filed April 17, 1922 Patented Dec. 29, 1925.

UNITED STATES PATENT 0FFlCE.'

BENJAMIN S. ELBOD, OF OMAHA, NEBRASKA, ASSIGNOB T0 ELBOD SLUG CASTING MACHINE COMPANY, OF OMAHA, NEBRASKA, A COBPOBATION OF NEBRASKA.

BAR-CASTING DIE AND METHOD FOR SEABONING THE SAME.

Application filed April 17, 1922. Serial No. 554,084.

To all whom it may concern:

Be it known that I, BENJAMIN S. ELRoD, a citizen of the United States, and a resident of Omaha, in the county of Douglas and State of Nebraska, have invented certain new and usefullmprovements in Bar-Casting Dies and .Methods for Seasoning the Same, of which the following is a specification.

My invention relates to machines for easting continuous bars of soft metal, particularly of type-metal and similar alloys, wherein the continuous bars are formed by extrusion or eduction, or both, through a die which is associated with cooling means by which the molten metal is solidified while passing through the mold-channel. My present invention is adapted especially for use with the dies employed in bar-casting machines of the type disclosed in my application, Serial No. 168,546, filed May 14, 1917, and in the application of Elrod and Hector, Serial No. 416,904, filed October 14, 1920. It is the object of my invention to provide a simple, efficient and inexpensive method of producing a die for the purpose stated, having upon'the surfaces 0 the die-channel in which the soft-metal bar is cast, a smooth, protective, permanently adherent, and substantially integral skin or layer of such composition as to have substantially no chemical afiinity for the soft metal which is cast in the die, whereby seizing, soldering or adhesion of the soft metal to the die is prevented. A further object of my invention is to produce a die having the above characteristics, without the same being first used in the machine through apreliminary or seasoning period.

In the accompanying drawings Fig. 1 is a side view of a die of the type with which my seasoning method is used, Fig. 2 is a transverse section of the same on the line 2-2 of Fig. 1, Fig. 3 is a longitudinal section on the line 3-3 of Fig. 2, and Fig. 4 is a sectional view of one of the die parts, representing diagrammatically the formation of the protective layer upon the working surface of the part.

In the construction of continuous barcasting machines of the type above mentioned, thedie or member forming the channel in which the bar is cast, or in which the molten metal is cooled to form the solid bar, is preferably made of cast-iron; it having been ascertained that this is the best matemal commonly available for the purpose and having the requisite characteristics of low, heat-expansibility, capability of bemg easily machined to form smooth and uniform surfaces, low chemical affinity for the type-metal or similar soft metals employed in casting the continuous'bars, and capability of seasoning to form upon the surfaces of the die-channel a composition or material which is substantially permanent and unaffected by the passage of the bar through the channel.

Referring to the drawings, the die there represented comprises two similar side pieces 5 and 6, between which are the two longitudinal liners or upper and lower spacing-strips 7 and 8, and a bafile or endplate 9 which partially closes the upper part of the mold-channel at the receiving end and constrains the molten metal to enter at the lower part of the channel. To compensate for the partial closing of the channel by the baffle or end-plate 9, the side-pieces 5 and 6 have opposite cylindro-segmental grooves 10 therein below said end-plate and extending from the receiving end of the die inwardly past the end-plate. The die-parts are secured together by a plurality of transversely extending screws 11, as shown. The here described and illustrated form of the die is the same as that employed in the machine described in'the application of Elrod and Hector, hereinbefore referred to.- In the use of the die there is supplied to the mold-channel, together with the molten metal, a limited quantity of lubricant, the same preferably being a heavy mineral oil, which facilitates, the eduction of the formed bar from the channel, in two ways, namely, by its action as a lubricant in reducing friction between the formed bar and the walls of the channel, and by tending to prevent seizing or soldering of the congealing soft metal to the metal from which the die is formed.

When a die of the class described is first used, without preliminary treatment by the method hereinafter set forth, the seizing or soldering of the bar to the die will occur with great frequency, notwithstanding the presence of lubricant. in the channel, although the introduction of an excessive quantity of the lubricant will limit the tendency. As the use of the die is continued,

it is found that the tendency to'adhesion between the bar and the die is progressively reduced, so that after a time no further adhesion will occur, even though the supply of lubricant be greatly reduce or for moderate eriods completely, discontinued. After reac ling such a condition, the die is said to be seasoned, and a special object of my.

present invention is to effect such seasoning of the die prior to its use in the machine, whereby to avoid the expensive and troublesome method of seasoning by intermittent actual use under excessive lubrication.

In carrying out my invention, the die is formed in the usual way, the parts being machined to size, and.the inner surfaces which are to form the walls of the die-channel being accurately ground or polished to form smooth and true plane-surfaces. When the parts are completed and otherwise ready for assembling, they are processed as follows: Each part is coated with a heavy mineral lubricating oil, preferably by immersion therein. The oil-coated part is then heated over the flame of an ordinary Bunsen gas-burner, such as represented at 12 in Fig. 4, there being presented to the flame that side of the part opposite the working face which forms a side of the diechannel in the assembled structure. As the part becomes heated the oil coating is vaporized, ignited and burned off, the heating of the working face being eflected principally by conduction through the body of the part from the opposite side which is presented to the burner-flame. When the size of the die-part is greater than the s read of the flame, the part may be move about sufficiently to insure substantially uniform heating thereof, and the heating is continued until the oil coating ;is entirely removed by its vaporization and burning, the operation being so controlled that the temperature of the part is not raised so as to show any color. That is to say, that during the entire operation the temperature of the part is below a red heat. If properly carried out, a single immersion of the part, and burning off of the oil coating, is suflicient .to effect the desired result, but the operation may be repeated should the appearance of the part after the first burning ofi indicate insuflicient formation of the protective composition upon the working surface. The working surface, after treatment, is black in color,

smooth and glossy, and there appears to be no added film or coating extending beyond the normal surface of the metal and removable by friction or abrasion insuflicient to remove a portion of the metal itself. It appers-that the residues of the oil penetrate the surface of the metal to some extent, or that a chemical union occurs between the metal at the surface and some element or elements derived from the oil, since the surface-com- LEB'P'AQI position is obviously not a mere oxide of the metal, formed by combintion thereof with oxygen derived from the air, although it is possible that there is a combination of metallic oxide with carbon or other material derived from the oil. Insufficient treatment or processing of the part is indicated by the appearance of the black, glossy surface irregularly or in spots or blotches. The thickness of the affected portion of the metal indicated at 13, in Fig. 4, is somewhat exaggerated, but it will be understood that the composition or structure of the material is changed to an appreciable depth below the surface. In a die of the form shown in the drawings, where the transverse section of the bar produced is a flat rectangle, only the side-pieces 5 and 6 need be subjected to the seasoning process, although the working edges of the parts 7, 8 and 9, which are exposed to the die-channel, may also be treated if desired. No appreciable change of the dimensions of the die-parts occurs, and the size of the die-channel formed by the assembly of the parts is the same after as before the treatment. The die, after being processed as described, may be placed in the machine and used immediately, without liability of adhesion or soldering of the soft metal thereto occurring. The processed or protected die-surface a pears to be substantially the same as is ormed when the die is seasoned by actual use in the machine, and the protected surfaces appear to be substantially unaffected by continued use in the machine, there being no appreciable wear of the surfaces as long as a normal amount of lubricant is supplied to the die-channel with the molten metal.

Now, having described my invention, What I claim and desire to secure by Letters Patent is:

1. An extrusion die, comprising bodyportions of cast-iron having at the working surfaces thereof and integrally united therewith the composition resulting from coatin said surfaces with heavy mineral bil an heating said body-portions to vaporize and burn off the oil coating.

2. An extrusion die, comprising bodyportions of cast iron having at the workin surfaces thereof and integrally united therewith the composition resulting from heating said body-portions, while said working surfaces are coated with heavy mineral oil, to temperatures high enough to vaporize the oil but below a red heat.

3. An extrusion die, comprising bodyportions of cast-iron having formed integrally therewith working surfacesof a black glossy composition consistin of the metal in combination with residues 0 heavy mineral oil volatilized in contact with the metal.

4. The method of pre-seasoning dies of the class described, consisting in applying to the workin surfaces thereof a coating of I "heavy minera oil, and heating the parts suf- 6. The method of pre-seasoning dies of the class described, consisting in coating the working surfaces of thedie-parts with heavy mineral oil, and then vaporizin said oil by heat applied principally throng the bodies of the arts.

7. The method of pre-seasoning dies of the class described, consisting in immersing the se arated parts of the diein heavy mineral oi removing the parts from the oil bath, and burnin ofi the adherent coating of oil by a flame irected at the sides of the parts respectively opposite the diechannel 1n the assembled structure.

8. The method of pro-seasoning dies of the class described, consisting in coating with heavy mineral 'oil the surfaces of the separate parts of" the die, and then heating the oil-coated parts until the coating is dissiparted by volatilization and burning.

9. The method of pre-seasoning dies of the class described, consisting in coatin the working surfaces with heavy minera oil, and heatin the die to temperatures below a red heat ut high enough to vaporize the oil.

10. The method of pro-seasoning dies of the class described, consisting in coatin the working surfaces with heavy minera oil, and then heatin the parts by a flame applied at the sur aces opposite said working surfaces, the temperatures attained being sufiicient to vaporize the oil at the working surfaces but being below a red heat.

BENJAMIN s. ELROD. 

